Mobile communication systems such as cellular telephones, personal digital assistants (PDAs), and handheld systems are now required to perform more sophisticated communication functions with multiple networks, as well as multimedia functions. For example, a multistandard wireless communication device, such as a cellular handset, may comprise a Bluetooth device for wireless PAN (personal area network) communication, a Wi-Fi device for wireless LAN (local area network) communication, and/or an application processor for playing music and capturing video. Each of the Bluetooth and/or Wi-Fi devices within the cellular handset, as well as the application processor, may utilize a main clock signal for normal mode of operation and a real-time clock signal for standby mode of operation. Consequently, each device within the multistandard wireless communication device may comprise a crystal and an oscillator to generate the main clock signal, and a crystal and/or an oscillator to generate the real-time clock signal. The increased number of crystals and oscillators for a multistandard handheld communication system may result in increased power consumption and cost of implementation.
In order to effectively maximize use of channel bandwidth while permitting a plurality of access devices to share the bandwidth, stringent timing requirements may be utilized by a communication device during synchronization with the network. For example, in GSM, a voltage controlled crystal oscillator (VCXO) may be utilized to generate a 13 MHz clock signal, whose frequency may be calibrated to match the network timing. However, in some communication networks, such as Bluetooth and Wi-Fi networks, network timing requirements may not require a VCXO to generate a clock reference signal.
Further limitations and disadvantages of conventional and traditional approaches will become apparent to one of skill in the art, through comparison of such systems with some aspects of the present invention as set forth in the remainder of the present application with reference to the drawings.